There have been active studies on estimation of human posture based on a captured moving picture. A posture estimation apparatus can determine a person's motions from a moving picture through computer analysis and thus can perform behavior analysis without involving manual works. Applications of behavior analysis include detection of unexpected behaviors on the street, analysis of in-store purchase behaviors, aid in work efficiency improvement at a factory, and form coaching in sports, for instance.
For example, PTL 1 discloses a technique of estimating a person's posture based on an image of the person captured using a monocular camera.
In the technique disclosed in PTL 1 (hereinafter, referred to as “related art”), first, candidates for a part are extracted based on an ellipse shape or parallel lines included in a captured image of the person. Then, in the related art, a part likelihood and a part relationship likelihood are calculated using a likelihood function statistically obtained from a plurality of sample images. Further, in the related art, an optimal combination of candidates for the part is calculated based on the calculated likelihood. Therefore, with the related art, it is possible to specify which part is located in which region, so that it is possible to estimate the person's posture regardless of a position or an orientation of the person.